Modular power distribution system for use in computer equipment racks

ABSTRACT

A modular power distribution system is provided for distributing power within an equipment rack. A control unit is mounted within the rack having a power input connected to a power source and a converter for converting the input power to a power supply for the rack equipment. The control unit includes a housing and power outlets are provided for electrical connection to the control unit and distributing the converted power supply to the equipment. One or more extension bars are mounted within the rack adjacent a corner support of the rack. The extension bar includes a power inlet and is connected via an electrical conductor to one of the power outlets of the control unit. The extension bar includes a number of power outlets (such as up to or more than 8) adapted for electrical connection to power supply lines (cords or hardwiring) from the rack equipment.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates, in general, to power distributionand distribution systems, and more particularly, to a modular powerdistribution unit for use in distributing power within the limited spaceof an equipment cabinet or rack, such as a computer equipment rack or adata storage cabinet.

[0003] 2. Relevant Background

[0004] In the computer industry, mass storage systems and other computersystems typically include numerous multi-shelf cabinets or racks eachholding multiple devices or enclosures, such as servers, disk drives,and other computer devices. These racks or rack systems are ideal formodular projects and are designed to accept standard sized deviceshaving relatively standard power requirements and communicationconnections. Generally, the outer case includes an aluminum or steelframework fitted with covers and a series of connectors at the rear fromwhich the devices or modules derive their power and exchangecommunication signals. The individual modules include a supportingchassis or housing that slides into the rack and is supported on guides,such as clip-in glides. Racks and rack systems are inherently flexiblebut are often expensive which drives users and rack manufacturers toefficiently use space within the rack or cabinet.

[0005] Each rack or cabinet typically only has a limited amount of spacethat is defined by or arranged into shelves. The shelves or shelflocations are configured to allow a device enclosure or module or othercomponents to be plugged into and supported within the rack. Typicalrack configurations call for 14 shelves although more shelves may beprovided such as up to 24 or more shelves. If shelves are arrangedvertically, a typical cabinet may have 14, 24, 32, or some other numberof shelves that each occupy a certain amount of rack space, such as 3retma (U) which is a standard mounting unit increment.

[0006] In practice, such as data centers, data storage, and the like,the racks are often densely packed with devices, such as servers, eachrequiring a primary power supply and a backup power supply forredundancy. For example, one arrangement uses up to 14-3U serverenclosures in a rack requiring up to 28-750 watt power supplies. Inanother rack configuration, 21-2U servers are installed in a rack with42-500 watt primary and redundant power supplies. A major challengefacing rack and equipment designers is how best to serve dense equipmentusers so as to provide increased power distribution while efficientlyusing the space within the rack to reduce cable clutter and connectionand supply confusion. In other words, it is desirable to reduce theamount of space required for power distribution units (PDUs) (e.g.,typically, a plurality of electrical receptacles to which electricalplugs of power cords can be connected and which are supplied by an inletA/C power source) and power cords from the PDUs to the devices on therack shelves to thereby free up rack U-space for more modules orenclosures.

[0007] Existing forms of power distribution require large volumes ofcabinet or rack space as numerous PDUs are provided and often mounted inthe rack that reduces the available shelves or U-space for computer orother desired components. For example, current PDU support requirementsoften call for as many as four to six 24 amp PDUs per rack, which leadsto some rack configurations being limited when a maximum number of PDUshave been installed in the rack. In addition to the space required forthe PDUs, large volumes of rack space may be required for the largenumber of power cords and other devices required to connect the PDUs tothe individual devices or loads on the shelves. Often, an enclosure ordevice is located on a shelf which is relatively distant from theclosest PDU which requires a long power cord to be snaked through therack to the enclosure or device. The number of the cables and PDUsincreases deployment complexity and can cause connection problems andmistakes. Additionally, after installation is completed, laterexpansions or modifications to the rack and power distributionarrangements are difficult to successfully implement.

[0008] Hence, there remains a need for an improved method and system fordistributing power within an equipment rack or cabinet that requiresless U-space, reduces the number and lengths and cost of connectingpower supply cords used in racks (i.e., provides improved cable or cordmanagement), is simple to customize, to install, and upgrade or latermodify, and reduces the total deployment cost.

SUMMARY OF THE INVENTION

[0009] The present invention addresses the above discussed andadditional problems by providing a modular power distribution system foruse in distributing power to devices, modules, and/or enclosures mountedwithin equipment racks or cabinets. The power distribution systemincludes two basic building blocks: a core or control unit and one ormore (and, typically 2 or 4) extension sticks or bars. The modulararchitecture allows a rack designer to custom configure a rack powerdistribution system based on their particular computer or otherequipment needs and power availability, which minimizes cable clutterand confusion and increases available rack space.

[0010] Generally, the modular power distribution system concentratescentral features of typical power distribution systems (e.g., a mainpower switch, circuit breakers, load groups, and power-on indication)into the core unit that is configured to be mounted at a remote locationwithin the rack or cabinet enclosure. The housing of the core unit isthin, such as 1U or less, and includes clips or brackets for mountingvertically on a side of the rack (e.g., a 0U mounting) or horizontally(e.g., a 1U or less mounting). The extension bars include a number(e.g., 1 to 8 connections are provided in some embodiments) of AC poweroutlets, receptacles, connectors, cord segments, or other devices forconnecting enclosures, modules, or devices in the rack to a powersource. The extension bars include clips or other fasteners for mountingonto one corner support of the rack, which avoids using rack U-space forthe extension bars while also enabling positioning of the bars at nearlyany height within the rack and typically, near the rack positions orshelves of the devices being powered to reduce the need for long lengthsof power supply cords and extend outlets along the entire or any desiredportion of the length of the rack.

[0011] In operation, the core unit provides protected outputs that feedpower to multiple high current outlets in the extension bars that can beused for connecting the high current loads, e.g., the enclosures,modules, or devices mounted on the shelves of the rack, to an acceptablepower supply or source. The extension bars each connect directly to thecore unit via a flexible power supply cord. The extension barseffectively locate the “fanning out” of the AC power in the rack closerto the loads and eliminates many power supply cords that were requiredin previous distribution arrangements. A wide range of capacities may beprovided according to the invention (such as 16 to 40 amps devices) andnumerous outlets may be provided in each modular power distributionsystem, such as 32 outlets with the used of 4 extension bars each having8 AC power outlets (which in turn may be any of several industrystandard connector families or be short power leads that connectdirectly to the load when it is desired to eliminate power cords).

[0012] More particularly, a power distribution system is provided fordistributing power to electrical or computer equipment in an equipmentrack. The system includes a control unit mounted within the rack havinga power input electrically connected to a power source (such as with acable or hardwired to an AC power source or facility source) and aconverter for converting the input power from the source to a powersupply required by the rack equipment. The control unit includes ahousing on which a plurality of power outlets or connections are mountedfor providing an electrical connection to the control unit and fordistributing the converted power supply to the equipment. An extensionbar is mounted within the rack typically adjacent one of the cornersupports of the rack. The extension bar includes a power inlet and isconnected via an electrical conductor or power cord to one of the poweroutlets of the control unit. The extension bar includes a number ofpower outlets (such as up to or more than 8) adapted for electricalconnection to power supply lines (cords or hardwiring) from the rackequipment. The control unit housing typically includes one or morebrackets for rigidly mounting the housing to the corner supports of therack. In some embodiments, the control unit is mounted vertically in a0U mounting with the thin (i.e., less than about 1U) cross-section ofthe housing positioned between two adjacent corner supports. In otherembodiments, the control unit is mounted horizontally in a less than 1Umounting with the thin cross-section of the house position horizontallybetween the corner supports.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a functional block diagram of a modular powerdistribution system according to the present invention;

[0014]FIG. 2 is a partial perspective view of one embodiment of amodular power distribution system, similar to FIG. 1, installed in atypical equipment rack or cabinet showing the side mounting arrangementof the core or control unit;

[0015]FIG. 3 is a perspective view similar to that of FIG. 2illustrating another embodiment of a modular power distribution systemshowing the “1U” or horizontal mounting arrangement of the core orcontrol unit;

[0016]FIG. 4 is a front perspective view of a core unit, as would beused in the systems of FIGS. 1-3;

[0017]FIG. 5 is a rear perspective view of the core unit of FIG. 4;

[0018]FIG. 6 is functional block diagram of equipment in a rackillustrating the use of a pair of control units of the invention toprovide primary and secondary or backup power to four enclosures, suchas servers; and

[0019]FIG. 7 is a functional block diagram similar to FIG. 6illustrating the use of a pair of modular power distribution unit of theinvention to distribute power to three enclosures, similar to FIG. 6,but also providing a number of other rack options or devices.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The present invention is directed toward modular powerdistribution systems for use in equipment racks, such as those typicallyutilized in the computer and data storage industries, and rack designsincorporating such modular systems. The modular systems are unique inutilizing two building blocks to allow ready field configuration andplacement of power outlets within a rack. The first building block iscontrol unit that provides the connecting point to a power supplyoutside the rack and includes a number of control and distributioncomponents such as main power switch, circuit breakers, load groups, andremote power monitoring and management (such as via a network like theInternet or other communication network). The control unit has a thinhousing with mounting brackets that allow the unit to be mounted eitherin a vertical or side mounting in the rack (“a 0U mounting”) that doesnot use any rack space or a horizontal or in-rack mounting (“a 1Umounting”) that uses a small portion of the rack space. The secondbuilding block is a set (e.g., 1 to 4 or more) of extension bars orsticks that are connected to the control unit and include a number (suchas 1 to 8 or more) of power outlets, receptacles, and the like todistribute power to numerous locations in the rack. Similar to thecontrol unit, the extension bars include housings with clips or bracketsthat allow the extension bars to be mounted on vertical structuralmembers (e.g., corner supports) of the rack at varied heights to placethe outlets near the rack loads, e.g., enclosures, modules, and otherrack-mounted devices and equipment. The modular system addresses theproblem of cable management by significantly reducing the number ofcords and cables required and reducing the lengths of cables in therack, which improves cooling in the rack and frees up additional rackU-space.

[0021] More specifically, FIG. 1 illustrates a modular powerdistribution system 100 in functional block form as the system 100 maybe integrated into an equipment rack 110. The equipment rack 110 may beany of a number of widely available equipment racks used in the computerand electronics industry, such as the Compaq Rack 9000 and 10000 Series.The rack 110 generally includes space or shelves on or in whichequipment modules or enclosures are positioned, with an industrystandard being 3 retmas equaling 1U. An important design configurationfor many racks is attempting to utilize all or most of the rack U-spaceor shelves with functional equipment (such as computer servers,controllers, and the like) and not with support or peripheral equipment,such as power distribution devices and power supply cables.

[0022] With this space requirement in mind, the power distributionsystem 100 includes a control or core unit 120 which centralizesnumerous power distribution, power distribution and load monitoring, andcontrol functions within a single device and includes one or more powersupply sticks or extension devices that provide power from the controlunit 120 to a number of loads or enclosures (not shown in FIG. 1)mounted throughout the rack 110. As will be discussed with reference toFIGS. 2-5, the control unit 120 typically includes a relatively smallhousing (such as 1U or less thickness) and mounting brackets compatiblewith standard racks 110. The combination of small size and mountingbrackets allows the control unit 120 to be mounted in numerous locationswithin the rack 110 in a vertical or side arrangement (“0U mounting)between two corner supports of the rack 110 that takes up no or littlerack U-space or in a horizontal or shelf arrangement (“1U mounting”)that takes only 1U or less of rack U-space.

[0023] The control unit 120 provides a power supply function within therack 110. The unit 20 is connected to power source 140 by power cord orcable 144. The control unit 120 functions to brings power into the rack110 from power source 140 (e.g., any of numerous power sources used inthe computer equipment and data storage industries) and then convertsthe power received from power source 140 to a power supply useful ordemanded by loads in the rack 110. To this end, the control unit 120includes converter 122 to convert the input power (such as 30 to 50 ampAC) on cable 144 for distribution on power supply cables 152, 156, 162,172 to extension bars 150, 154, 160, 170.

[0024] The control unit 120 provides protected outputs that feed powervia the converter 122 to multiple current outlets (typically, highcurrent outlets) on the control unit 120 that can be used to connect toindividual high current loads (not shown in FIG. 1 but see FIG. 6) or tothe extension bars 150, 154, 160, 170 via flexible cords 152, 156, 162,172, respectively. Each extension bar 150, 154, 160, 170 includesmultiple power outlets (e.g., AC power outlets) to locate the “fanningout” of the AC power closer to the load and eliminate multiple long runsof individual power cords. The power outlets may be any of numerousindustry standard connector families or be short power leads that canconnect directly to the load to eliminate the need for power cords. Aswill discussed with reference to FIG. 2, the extension bars 150, 154,160, 170 are configured for mounting on corner supports of the rack 110with clips or other brackets and may be mounted at user-selected heightsto allow ready customization of the power distribution system 100 and toplace the extension bars, and therefore, power outlets, near to loadswithin the rack 110.

[0025] The number of extension bars 150, 154, 160, 170 may be four, asshown, or any other useful number (such as 1, 2, 3, 4, 5, or more) aslong as the total current does not exceed the maximum allowable currentdraw or current rating of the control unit 120. Similarly, the number ofpower outlets can vary, and in one embodiment, 8 outlets are provided oneach extension bar 150, 154, 160, 170, which provides 32 outlets (orsupport for 32 loads) with one control unit 120. A receptacle fan-outdevice 178 may be connected to an extension bar, such as bar 170, toenable additional loads to be supported by the power distributionassembly 110. The device 178 may be any industry accepted power supplydevice, such as typically plug-in outlet centers, power outlet strips,UPS products, and the like.

[0026] To fulfill this power supply or distribution function, numerousconfigurations can be used for the control unit 120 and converter 122and for the extension bars 150, 154, 160, 170 (as well as the number ofsuch bars or sticks). The embodiments may range from lower input powerdensity (such as a 16 amp input with 1 or 2 expansion bars) up to highinput power density (such as 3-phase input supporting up to 6 extensionbars). With this broad range of inputs and outputs, the following arejust a few exemplary (but not limiting) examples of how the powerdistribution function may be provided in a system 100. One embodiment isdesigned to connect low voltage (i.e., 100 to 127 AC voltage) powersources and/or directly into a facility outlet (i.e., power source 140)via cord 144 and a single input on unit 120 (such as a NEMA L5-30P orthe like) and four outputs (such as four IEC320-C19 outlets at 12 ampseach). This embodiment typically has a relatively low maximum current orcurrent rating (such as 24 amps) with the output being up to 32 outletssuch as 8 NEMA 5-15 or other outlets on the bars 150, 154, 160, 170 withmaximum outlet and bar currents (such as 12 amp maximum per outlet and12 amp maximum per bar).

[0027] In another embodiment of system 100, a higher input voltage (suchas 200 to 240 AC voltage) is input via cord 144 from power source 140,which is typically the facility input, and having four outputs (such asfour IEC320-C19 outlets at 12 amps each). In this embodiment, themaximum through current may again be set at 24 amps with each extensionbar 150, 154, 160, 170 having up to 8 IEC 320 C-13 or other outlets withmaximum outlet and total extension bar currents (such as 10 amps peroutlet and 12 amps per bar). In another embodiment, the maximum currentthrough the control unit 110 is set at 32 amps with single input (suchas an IEC 309-32A) provided in the control unit 110 with four outletsfor connecting to power supply cords 152, 156, 162, 170 and eachextension bar 150, 154, 160, 170 having 8 outputs or outlets (such as 8IEC 320 C-13 or similar outlets). In another example, the control unit110 is designed to hardwired via cord 144 to the power source 140 (suchas the facility input or a high voltage UPS). The input connection onthe unit 110 then may be a field wired terminal and the maximum currentfor the unit 110 may be higher, such as 40 amps and the input voltagehigher, such as 200 to 240 volts AC. In this example, the extension bars150, 154, 160, and 170 may not be identical with three having 8 outlets(such as 8 IEC 320 C-13 outlets with a maximum outlet current such as 10amps) with a particular maximum bar current (such as 12 amps) and withthe fourth bar having fewer outlets (such as 4) with but with highercurrent ratings (such as 4 IEC 320 C-19 outlets having a 12 amp rating).In this manner, loads having differing power input requirements can bemounted within a single rack 110 and supplied power effectively with acontrol unit 120 with differently configured extension bars 150, 154,160, 170. These are just a few examples of the configurations for thepower distribution system 100 and are not intended to be limiting but todemonstrate the flexibility of the system 100 to distribute power atvarying locations and to differing types of loads within the rack 110.

[0028] As shown, the control unit 120 includes an overload protector 124and output circuit breakers 126 to more effectively provide the powerdistribution function in the system 100. More particularly, the overloadprotector 124 and output circuit breakers 126 provide input overcurrentprotection, surge protection, and load segment output overcurrentprotection. The overload protector 124 may be any device or circuitthat, for example, disconnects the control unit 120 from the powersource 140 when the current or voltage becomes excessive (over designlimits for the control unit 120). The output circuit breakers 126 areprovided to open the circuit to the outlet receptacles or connections tothe extension bars 150, 154, 160, 170 via cords 152, 156, 162, 172, andthe number and rating of the output circuit breakers 126 may vary tosuit the allowable current in the bars 150, 154, 160, 170 (e.g., in 12amp embodiments of the bars, 15 amp or smaller circuit breakers may beprovided for each outlet receptacle in the control unit 120). Althoughnot shown, the control unit 120 may include line fail-over switchingdevices or circuits along with multiple utility feeds for redundantpower supply or source configurations (e.g., by adding an additionalpower source 140 and source line 144).

[0029] In addition to rack power distribution functions, the controlunit 120 in some embodiments is configured to facilitate a number ofremote monitoring and/or remote management or operation functions.Generally, such remote management and monitoring functions may includeload segment control (e.g., on/off control), automatic or manualstaggered startup of each output from the control unit 120, line statusmonitoring, line voltage measurements, power consumption monitoring, andother desired management and monitoring functions. An operator ormonitor can view the results of such monitoring and remotely operate thecontrol unit 120 from remote monitoring and control node 190 (such as atypical computer device with I/O devices such as keyboards, graphicaluser interfaces, and the like, with a processor and memory, and amonitor). Operator node 190 is linked to the control unit 120 via thecommunication network 180, e.g., any digital data communicationsnetwork, wired or unwired, such as the Internet, a local area network(LAN), a wide area network (WAN), and the like, and communication links182 and 186. Alternatively, local management via the user node 190 maybe provided with a direct connection (such as at a serial interface 132at the control unit 120 to monitoring and/or management cards in theunit 120).

[0030] A communication interface 132 is provided at the control unit 120to handle input and output functions and to facilitate communicationwith the user node 190. For example, the communication interface 132 maybe a Web or Internet Protocol (IP) interface and the user node 190 mayinclude a Web browser for accessing and communicating with thecommunication interface 132. Communications over the network 180 can beimplemented using simple network management protocol (SNMP) or otheruseful protocols that facilitate management applications (such as thosethat would be operating on node 190) to query or command managementagents on the control unit 120 (such as those embodied in the remotemonitoring unit 128 and/or the remote management unit 130).

[0031] The remote monitoring unit 128 is provided to monitor a number ofparameters during the operating of the control unit 120. For example,the remote monitoring unit 128 may include measurement sensors for senseline voltages at outlets or in lines 152, 156, 162, 172 to extensionbars 150, 154, 160, 170 and in response, to communicate or transmit asignal(s) to the remote monitoring and management node 190 viacommunication interface 132. Sensors may also be provided to measureline status or on/off status of the lines 152, 156, 162, 172 and powerconsumption on these lines 152, 156, 162, 172 to measure operations atthe extension bars 150, 154, 160, 170 and connected loads or rackequipment. Again, these operating measurements are communicated to thenode 190 via the communication interface 132.

[0032] The remote management unit 130 provides operating managementfunctions for the control unit 120 including local (or automaticcontrol) and remote control functions including distributing power inresponse to commands from the node 190 (or at an interface on the unit120 (not shown)). The automatic controls may include staggered startupof each output or extension bar 150, 154, 160, 170. The remotemanagement features may include intelligent segment control such asremotely providing or terminating power to one or more of the extensionbars 150, 154, 160, 170. More specifically, the remote managementcommands for the outlets may include configuration of each of theoutlets of the control unit 120 (such as via SNMP and interface 132),immediate on, sequenced on, delayed on, immediate off, and reboot (e.g.,turning an outlet off and then back on immediately or with delays).Shutdown commands may also be issued to the control unit 120 to turn offall outlets. Other useful management commands may be issued by the node190 and processed by the remote management unit 130, such as a cancelcommand to stop action on the most recent command and an overridecommand to cancel a previous command and replace it with a new command.

[0033]FIG. 2 illustrates one physical implementation and mountingarrangement for a modular power distribution system in a rack. As shown,a modular power distribution system 200 is installed in a rack 210 inthe vertical or 0U-mounting arrangement to limit the amount of rackU-space being used by the system 200 (e.g., to consume no or very littlerack U-space). The rack 210 is a standard equipment rack with side wallshaving a row or strip 216 of mounting slots 216 and with corner supports214 also including mounting holes or slots. As shown, the control unit220 has its substantially planar housing 221 arranged vertically (i.e.,with a plane passing through the housing being substantially parallel tothe side walls of the rack 210). Mounting brackets or clips 226, 228 areprovided on the ends of the housing 221 of the control unit 220 forrigidly clipping to or mating with the holes or slots in the cornersupports 214. While shown in a generally upper position within the rackor cabinet 210, the control unit housing 221 can be mounted at anyuseful position or height within the rack 210. Outlet on/off switches222 are provided on the housing 221 and a control unit on/off switch 224is also included to allow local, manual control of the powerdistribution to the outlets of the housing 221 to which the power supplycords 252, 256, 262, and 272 are connected at housing 221. Power issupplied to the control unit 220 via inlet power cord 244 which isconnected to a power source or supply (not shown) external to the rack210.

[0034] The illustrated system 200 fans out power distribution within therack 210 by including four power extension bars 250, 254, 260, 270 thatare connected to control unit 220 with power supply cords 252, 256, 262,272. The power extension bars 250, 254, 260, 270 may be configuredsimilarly to the bars 150, 154, 160, 160 with similar maximum currents,with outlets or receptacles (such as with 8 outlets or receptacles asshown) or cord segments, and other described features. The bars 250,254, 260, 270 can be mounted at any position or height within the rack210 (typically, adjacent planned loads or equipment positions on theshelves). The configuration of the bars 250, 254, 260, 270 allowsmounting within the rack 210 without consuming rack U-space as the bars250, 254, 260, 270 have generally square or rectangular cross sectionsthat are similar in size to the corner supports 214, such that the bars250, 254, 260, 270 either extend only slightly beyond the cornersupports 214, are coplanar, or are actually recessed from the surfacesof the corner supports 214. As shown for bar 270, mounting clips orbrackets 274, 276 are provided on the ends of the bar 270 for rigidlymounting the bar 270 to the row 216 of mounting holes or slots on theside wall of the rack 210, which provides flexibility in the positioningof the bar 270 at nearly any position within the rack 210. As shown,cable management is significantly improved with only four short supplycables 252, 256, 262, 272 being used to supply 32 outlets (at least inthis embodiment) from which 32 loads can be supplied with relativelyshort jumpers.

[0035]FIG. 3 illustrates some of the mounting and configurationflexibility provided by the modular power distribution systems of theinvention. A power distribution system 300, with several similarcomponents, is shown installed in the rack 210. As shown, the housing221 of the control unit 220 is mounted horizontally in the rack 210 withmounting clips 226, 228 being used to mount the housing 221 to cornersupports 214. The housing 221 is relatively thin so as to take up aslittle rack U-space as possible while still providing desired functions(such as 1U, 0.5U, or less thickness). In one embodiment, the housing221 is about 17.5 inches by about 1.62 inches by about 13 inches (widthby height or thickness by depth). The depth may be maintained at lessthan half the depth of the rack 210 to allow two control units 220 to bemounted back to back, horizontally, which is useful in modular powerdistribution systems that utilize two control units 220 to distributepower in a rack 210. Alternatively, when two units 220 are installed ina single rack 210, the units 220 may be mounted adjacent to each otherbut top to bottom or be mounted in a spaced apart fashion at twodiffering locations within the rack 210. In the system 300, only twoextension bars 260, 270 are provided and are attached to the controlunit 220 by cords 262, 272, respectively. Of course, more or fewerextension bars may be utilized in the system 300 (or in system 200).

[0036]FIGS. 4 and 5 illustrate one embodiment for a control or core unit420 (such as would be used in systems 100, 200, and 300). As shown, thecontrol unit 420 includes a housing 421 that is rectangular in shape andhas a thickness or height, H that is selected to allow the control unit420 to be mounted either in a vertical or horizontal mounting (asdescribed in FIGS. 2 and 3) without requiring much if any rack U-space.In most embodiments, the thickness or height, H, is less than or equalto about 1U and in some embodiments is less than about 0.5U to allowstacking of 2 control units on a single shelf. The thinness of thehousing 421 enables 1U or less horizontal mounting, which leavesdesirable rack U-space for other equipment in a rack.

[0037] As shown, a main ON/OFF switch 424 is provided for shutting downthe control unit 420 along with a main indicator light 430 forindicating when power is provided to the unit 420 and when the switch424 is placed in the ON position. An outlet switch or circuit breaker(such as a 15 amp circuit breaker) 422 is provided for each power outletof the unit 420 (in this case 4 outlet switches 422 are provided tocontrol, and in the case of circuit breakers to overcurrent and surgeprotect, outlets 450). Although not shown, indicator lights may beprovided for each of the outlet switches 422. Power is supplied to thecontrol unit 420 by an attached input power cord (which may, in someembodiments, be replaced by hard wiring directly to a facility input)444 which is connected to the housing 421, such as by a protective earthbonding screw 445. The power cord 444 is also attached to a power sourceor supply (such as a facility AC power source). Power outlets 450 areprovided to allow connection with standard power cords to extensionstrips or bars, and the number and type of outlets 450 may be varied topractice the invention. As shown, four outlets 450 (such as 4 IEC C19outlets) are provided to support power distribution to up to fourextension bars. In remote monitoring and/or management embodiments (suchas that shown in FIG. 1), a plug-in for an interface connection isprovided for a communication signal cable to a network and/or remotemonitoring and control node, e.g., a SNMP or other connection.

[0038]FIGS. 6 and 7 illustrate two power distribution systems 600 and700 that illustrate the flexibility of the invention in allowing a userto configure power distribution in differing, modular ways to meet theirrack power needs. In a rack in the data storage and other industries, atypical power system block diagram may call for a primary and a backupAC input to three, four, or more high current loads.

[0039] In FIG. 6, two control units 620 and 630 without extension barsare used to provide the AC transfer switch function or powerdistribution (from primary and backup power sources not shown) to theloads. As shown, a modular power distribution system 600 includes a rack610 in which a primary control unit 620 and a backup control unit 630are mounted (either vertically or horizontally at a desired height inthe rack 610). Four enclosures (such as servers or other computing ordata storage device) 640, 650, 660, 670 are also mounted in the rack 610and are configured for redundant power supplies with primary and backupinlets 642, 644, 652, 654, 662, 664, 672, 674, respectively. Duringnormal operations, the primary control unit 620 distributes power to theenclosures 640, 650, 660, 670 via power supply cords 624 that areconnected individually to the power outlets 622 of the primary controlunit 620 and to the primary inlets 642, 652, 662, 672. The backupcontrol unit 630 supplies backup power via power supply cords 634 thatare connected individually to the outlets 632 and the backup inlets 644,654, 664, 674 on the enclosures 640, 650, 660, 670.

[0040] An alternate modular power distribution system 700 is shown inFIG. 7 that demonstrates how the combined use of control units withextension bars is useful for fanning out pluggable or other powersupplies within a rack without cable confusion or loss of rack U-space.As shown, the system 700 includes a rack 710 in which three enclosures,such as high current loads including servers and the like, 740, 750, 760are mounted along with a number of other rack devices 770. The highcurrent loads 740, 750, 760 are provided redundant power directly from aprimary control unit 720 and a backup control unit 730. This is achievedby connecting primary inlets 742, 752, 762 via cables 726 to outlets 724on the primary control unit 720 and by connecting backup inlets 744,754, 764 via cables 736 to outlets 734 on the backup control unit 730.

[0041] Significantly, the other rack devices 770 are also providedredundant power via extension strips 780 and 790 that are connected viacables 726, 736 to outlets 724, 734 on primary and backup control units720, 730. The extension strips 780 and 790 have outlets 784, 794 (suchas 8 outlets or receptacles) that are then connected by jumpers or hardwiring to the other rack devices 770. Through the use of extensionstrips 780, 790, a number of enclosures 740, 750, 760 and other rackdevices 770 can be powered from one or two control units 720, 730 withminimal cables, with reduced cable run lengths, and with increasedavailable rack U-space (as the control units 720, 730 can be verticallymounted in a 0U mounting or horizontally mounted in a 1U or lessmounting and as the extension strips 780, 790 are corner mounted so asto not use an rack U-space).

[0042] As can be appreciated, the modular characteristics of thecombined use of a core control unit with one or more sticks or stripssignificantly enhances flexibility in growth (e.g., larger capacityand/or more features) and provides simplified maintainability. Regardingflexibility, once a power distribution system is installed a user isable to upgrade the features and/or capacity in the control unit bysimply replacing the unit without modifying or replacing other portionsof the system, such as the extension strips which can remain in placeconnected to their loads. The extension strips or sticks can beunplugged from the core or control unit and the control unit can bereplaced with a control unit of greater capacity (e.g., a 16 amp unitcan be upgraded or changed to a 24, 32, or 40 amp core or vice versa) ora control unit with more or different control or power distributionfeatures or functionality, such as one with remote monitoring andmanagement features. In contrast, existing power distribution systemstypically require replacement of the entire power distribution systemand wiring the new system. Maintainability is improved because adefective part can simply be replaced without disturbing othercomponents of the power distribution systems of the present invention.For example, if an extension stick becomes defective, only thatextension stick needs to be replaced or repaired and if a coremalfunctions, the core can be readily replaced without the need forrewiring power distribution to loads or to the sticks.

[0043] Although the invention has been described and illustrated with acertain degree of particularity, the present disclosure has been madeonly by way of example and that numerous changes in the combination andarrangement of parts can be resorted to by those skilled in the artwithout departing from the spirit and scope of the invention. A systemaccording the invention, such as system 100 of FIG. 1, may include 2 ormore control units within a single rack 110 each connected to extensionbars to quickly increase the number of power outlets within a rack, toincrease the modularity of power distribution control and distribution,and to allow differing loads to be powered within a single rack (i.e.,through the use of 2 different control units with different outputcharacteristics). In some embodiments of the invention, a single type ofextension bar is utilized while in some arrangements it is useful toprovide 2 or more differing extension bars, such as extension bars withdifferent numbers and/or types of outlets or including cord segments forsupplying power to various loads in a rack. While specific voltagesand/or currents have been described, the modular power distributionsystems are by nature voltage independent and worldwide compatible. Thepower distribution system typically conforms with power distributionindustry standards, e.g., conform to standards such as the NationalElectrical Code (e.g., NFPA 70) and the Standard for Safety ofInformation Technology (e.g., UL 1950, Standard for Safety ofInformation Technology Equipment, and/or IEC950).

I claim:
 1. A power distribution system for distributing power toelectrical or computer equipment mounted within an equipment rack oncorner supports, comprising: a control unit mounted within the rackincluding a power input for receiving power from a power source locatedoutside the rack, a power converter for converting the received power toan output electrical power, and a plurality of power outlets forproviding an electrical connection to the control unit and outputtingthe output electrical power; an extension bar mounted within the rackadjacent one of the corner supports and having an electrical power inputfor input of electrical power to the extension bar and a plurality ofpower outlets adapted to couple with and distribute electrical power toconducting elements that electrically connect the extension bar to themounted equipment; and an electrical power cable connected to one of thepower outlets in the control unit and to the electrical power input ofthe extension bar.
 2. The system of claim 1, wherein the control unitincludes a housing to which the control unit power outlets are mountedand brackets connected to ends of the housing configured for supportingthe housing at a selectable height within the cabinet on two adjacentones of the corner supports, whereby 0U of rack U-spacing in theequipment rack is utilized by the housing.
 3. The system of claim 1,wherein the control unit includes a housing to which the control unitpower outlets are mounted and brackets connected to the housingconfigured for supporting the housing in a horizontal position betweenthe corner supports and wherein the housing has a thickness of less thanabout 1U.
 4. The system of claim 1, further including a second extensionbar within the rack adjacent one of the corner supports and having anelectrical power input for input of electrical power to the secondextension bar and a plurality of power outlets adapted to couple withand distribute electrical power to conduction elements that electricallyconnect the second extension bar to the mounted equipment.
 5. The systemof claim 4, wherein the power outlets of the second extension bar differfrom the power outlets of the extension bar.
 6. The system of claim 1,wherein the control unit includes overload protection and an outputcircuit breaker for each of the power outlets in the control unit. 7.The system of claim 1, wherein the control unit includes a networkcommunication interface and is communicatively linked to a remotemonitoring and management node via a communication network and thecommunication interface.
 8. The system of claim 7, wherein the controlunit includes a monitoring system for sensing operating parameters forthe control unit and in response, transmitting monitoring signals to theremote monitoring and management node.
 9. The system of claim 8, whereinthe operating parameters are selected from the group consisting ofoutput line status, power consumption at the power outlets, and outputline voltage.
 10. The system of claim 7, wherein the control unitincludes a management system responsive to command signals from theremote monitoring and management node to operate the control unitincluding selective power distribution to the power outlets.
 11. A powerdistribution system for mounting within an equipment rack to distributeelectrical power to devices mounted within the equipment rack from anelectrical power source external to the equipment rack, comprising: anelongate first extension bar having a power inlet and a plurality ofpower output connectors adapted to couple with electrical conductorelements that electrically connect each of the power output connectorswith one of the mounted devices and further including means for mountingthe first extension bar in a first position adjacent to andsubstantially parallel to a corner support of the rack; an elongatesecond extension bar having a power inlet and a plurality of poweroutput connectors adapted to couple with additional ones of theelectrical conductor elements that electrically connect each of thepower output connectors with one of the mounted devices and furtherincluding means for mounting the second extension bar in a secondposition adjacent to and substantially parallel to the corner support ofthe rack; a control unit mounted within the rack including a power inputfor receiving power from the external power source and a plurality ofpower output connectors to output the received power and to couple withelectrical conductor elements that electrically connect a first one ofthe power output connectors with the power inlet of the first extensionbar and a second one of the power output connectors with the power inletof the second extension bar.
 12. The system of claim 11, wherein thecontrol unit includes a housing with means for rigidly mounting thehousing to two adjacent ones of the corner supports of the rack andwherein the housing has a thickness less than about a thickness of thecorner supports, whereby 0U of rack U-spacing in the equipment rack isutilized by the housing.
 13. The system of claim 11, wherein the controlunit has a current rating selected from the range of about 16 amps toabout 40 amps.
 14. The system of claim 11, wherein first and secondextension bars include at least six of the power output connectors. 15.The system of claim 11, further including a third and a fourth extensionbar each having a power inlet and a plurality of power output connectorsadapted to couple with additional ones of the electrical conductorelements that electrically connect each of the power output connectorswith one of the mounted devices and further including means for mountingthe second extension bar in a second position adjacent to andsubstantially parallel to the corner support of the rack and each havingtheir power inlets connected via an electrical conductor element to oneof the power output connectors of the control unit.
 16. The system ofclaim 11, wherein the control unit includes a network communicationinterface and is communicatively linked to a remote monitoring andmanagement node via a communication network and the communicationinterface.
 17. The system of claim 16, wherein the control unit includesa monitoring system for sensing operating parameters for the controlunit and in response, transmitting monitoring signals to the remotemonitoring and management node.
 18. The system of claim 17, wherein theoperating parameters are selected from the group consisting of outputline status, power consumption at the power outlets, and output linevoltage.
 19. The system of claim 16, wherein the control unit includes amanagement system responsive to command signals from the remotemonitoring and management node to operate the control unit includingselective power distribution to the power outlets.